fix(emulated): pad the input of the inverse hint to NbLimbs - #1855
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InverseHint requires the value on NbLimbs limbs, but computeInverseHint forwarded the element's limbs as they are. An element stored on fewer limbs, such as a Select between two small constants, made the hint fail with "inputs missing". Pad the input limbs with zeros before calling the hint.
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Field.Inversefails for a non-constant element that is stored on fewer limbs thanNbLimbs(), for example the result ofSelectbetween two small constants.Div,Mul,SqrtandExpon the same element work.Before:
NewHint: inputs missing(r1cs, scs and the test engine).After: solves, result checked against
ModInverse.computeInverseHintappends the element's limbs as they are, whileInverseHintrequires2 * NbLimbsinputs after the header (modulus, then value).computeDivisionHintpasses the limb counts explicitly, which is why division is not affected. This pads the value with zero limbs incomputeInverseHint, so the hint's input layout is unchanged.Test:
TestInverseShortElement(both branches of the select, test engine + compiled r1cs/scs), fails on master.std/math/emulated,sw_emulatedandinternal/statspass.